A flame-retardant and high-temperature resistant material for fireproof air ducts and its preparation method

Abstract

The invention discloses a flame retardant and high temperature resistant material for fireproof air duct and its preparation method, which comprises the following raw materials by weight: 60-70 parts of magnesium oxide, 35-45 parts of magnesium sulfate, 45-60 parts of water, 15-25 parts of expanded perlite, 10-15 parts of mica powder, 10-15 parts of modified mineral fiber, 8-12 parts of quartz powder, 3-5 parts of silica fume, 0.5-0.8 parts of retarder, and 1-1.5 parts of waterproof modifier. The flame retardant and high temperature resistant material of the fireproof air duct is a multi-component composite inorganic material system, which is based on magnesium sulfate cement with natural fireproof advantages, optimizes basic physical properties by compositely using multiple functional fillers such as lightweight, heat-resistant and active, and adds modified mineral fiber prepared by a specific method as a key reinforcing phase, significantly improving the mechanical properties and structural stability of the material at high temperatures, so that the prepared material has good flame retardancy, high temperature resistance, good mechanical properties, light weight and durability, and is particularly suitable for fireproof air duct materials.

Description

Technical Field

[0001] The present invention belongs to the technical field of building materials, and in particular relates to a flame retardant and high temperature resistant material for fireproof air ducts and a preparation method thereof. Background Art

[0002] Air ducts are widely used in commercial buildings, industrial facilities, residential buildings, public spaces, and special venues to transport and distribute air, ensuring indoor air quality and comfort. With the advancement of building technology and increasing demand for air quality, duct systems are also evolving, moving towards greater efficiency, energy conservation, and environmental friendliness. Among them, fire-resistant ducts, also known as fire-resistant ducts, are duct systems specifically designed to maintain structural integrity and functionality in the event of a fire. They are widely used in high-rise buildings, underground facilities, tunnels, and other locations with strict fire protection requirements. Their primary function is to prevent flames and harmful gases from spreading through the duct in the event of a fire, protecting personnel and minimizing property damage.

[0003] Fire-resistant air ducts used in buildings primarily fall into two categories: galvanized iron ducts and inorganic fiberglass ducts. While these ducts meet the combustion performance requirements of the materials used in fire protection regulations, their fire resistance is less than ideal. During a fire, they are prone to distortion, collapse, cracks, and holes, allowing flames and smoke to penetrate the damaged ducts and spread the fire. Furthermore, iron ducts are prone to rust and damage, while inorganic fiberglass ducts are susceptible to moisture, aging, and deformation. These drawbacks severely impact the service life of these ducts in real-world applications and increase maintenance and repair costs.

[0004] Chinese patent application CN102515678A discloses an algae-calcium composite material, decorative board, and production method. The algae-calcium composite material comprises diatomaceous earth and a hydrated gel of a calcium-containing inorganic building material matrix. The calcium-containing inorganic building material matrix is one or more of calcium sulfate hemihydrate, calcium phosphate, and calcium aluminate. The components are preferably combined by weight in a ratio of 100:10-50:1.2-2.0:50-65:5-10 for calcium-containing inorganic building material matrix:diatomaceous earth:chopped reinforcing fiber:water-based adhesive solution:tributyl phosphate. The raw materials are pretreated, mixed, poured, molded, cured, dried, and surface treated to create the decorative material product. This composite material fully utilizes the excellent plasticity and environmental compatibility of the new composite material, while utilizing the diatomaceous earth's microporosity to impart environmentally friendly properties such as humidity control, adsorption of harmful gases such as formaldehyde, and sterilization. Chinese patent application CN114412130A discloses a fireproof board and ventilation duct, wherein the fireproof board comprises a fireproof layer and an outer layer. The outer layer is fixed to one side of the fireproof layer, and the side of the fireproof layer in contact with the outer layer is provided with sound-absorbing holes filled with sound-absorbing material. The fireproof layer comprises component A, a curing agent, and an adhesive. The fireproof layer is formed by mixing component A, perlite, and expanded vermiculite, pouring the mixture into a forming mold and pressing it. The fireproof board exhibits excellent fireproof and thermal insulation properties and is environmentally friendly, low-carbon, energy-saving, and renewable. The ventilation duct comprises a duct body and fireproof boards disposed on the inner and outer surfaces of the duct body. The ventilation duct effectively prevents fires and avoids the risk of ignition in the event of a fire. However, neither of the above patents nor the above technologies address the flame retardancy, high-temperature resistance, and mechanical properties of the fireproof duct material, and its overall performance needs to be improved.

[0005] Therefore, the deficiencies of existing fireproof duct materials in terms of flame retardancy and high temperature resistance have restricted the improvement of building fire safety. Therefore, it is of great significance to develop a fireproof duct material that is highly flame-retardant, high temperature-resistant, lightweight, environmentally friendly, and easy to construct. Summary of the Invention

[0006] In view of the deficiencies in the prior art, the object of the present invention is to provide a flame retardant and high temperature resistant material for fireproof air ducts and a preparation method thereof.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] A flame retardant and high temperature resistant material for fireproof air ducts, comprising the following raw materials in parts by weight:

[0009] 60-70 parts of magnesium oxide, 35-45 parts of magnesium sulfate, 45-60 parts of water, 15-25 parts of expanded perlite, 10-15 parts of mica powder, 10-15 parts of modified mineral fiber, 8-12 parts of quartz powder, 3-5 parts of silica fume, 0.5-0.8 parts of retarder, and 1-1.5 parts of waterproof modifier.

[0010] In the present invention, the flame-retardant and high-temperature resistant material used for fire-proof air ducts is a multi-component composite inorganic material system, which is based on magnesium sulfate cement with natural fire-proof advantages. It optimizes the basic physical properties by compositely using a variety of functional fillers such as lightweight, heat-resistant, and active, and adds modified mineral fibers prepared by a specific method as a key reinforcing phase, which significantly improves the mechanical properties and structural stability of the material at high temperatures; at the same time, by adding a certain amount of chemical admixtures to regulate the construction performance (slow setting) and improve durability (waterproofing), so that the prepared material has good flame retardancy, high temperature resistance, good mechanical properties, light weight, and durability, and is particularly suitable for fire-proof air duct materials.

[0011] Preferably, a flame-retardant and high-temperature resistant material for fireproof air ducts includes the following raw materials, by weight: 65-70 parts of magnesium oxide, 40-45 parts of magnesium sulfate, 50-55 parts of water, 10-25 parts of expanded perlite, 12-15 parts of mica powder, 13-15 parts of modified mineral fiber, 8-10 parts of quartz powder, 3-4 parts of silica fume, 0.7-0.8 parts of retarder, and 1.2-1.5 parts of waterproof modifier.

[0012] Preferably, the retarder is one or both of sodium tetraborate and sodium citrate, and the waterproof modifier is one or both of calcium stearate and zinc stearate.

[0013] Preferably, the method for preparing the modified mineral fiber comprises the following steps:

[0014] S1. Adding basalt fiber to a nitric acid solution for impregnation treatment, filtering, washing, and drying after the treatment to obtain pretreated basalt fiber; adding the pretreated basalt fiber to ethanol, followed by adding phenolic resin, stirring at a constant temperature, filtering, and drying after the stirring to obtain organic basalt fiber;

[0015] S2, adding the organic basalt fiber prepared in step S1 to deionized water, followed by adding boric acid and melamine, and performing a hydrothermal reaction. After the reaction is complete, filtering, washing, drying, and calcining are performed to obtain a composite fiber;

[0016] S3, adding the composite fiber prepared in step S2 to an ethanol aqueous solution, then adding γ-mercaptopropyltrimethoxysilane, stirring and reacting, filtering, washing, and drying after the reaction is completed to obtain an organic composite fiber;

[0017] S4, adding the organic composite fiber in step S3 into toluene, and then adding lauryl methacrylate and azobisisobutyronitrile, and reacting at a constant temperature. After the reaction is completed, filtering, washing, and drying to obtain modified mineral fiber.

[0018] Preferably, in step S1, the mass concentration of the nitric acid solution is 15-20%, the temperature of the immersion treatment is 30-40°C, and the time is 1-2h; the mass ratio of the pretreated basalt fiber, ethanol, and phenolic resin is 50-60:300-400:20-30, and the temperature of the constant temperature stirring is 60-70°C, and the time is 1-2h.

[0019] In the present invention, the surface roughness and specific surface area of the basalt fiber are increased through nitroester impregnation treatment, thereby improving the subsequent bonding performance with the phenolic resin. The phenolic resin is then used as a coating layer, and its high residual carbon rate is converted into a relatively dense carbon layer through high-temperature cracking during the subsequent calcination process. This carbon layer can serve as a transition layer or bonding layer between the boron nitride and the basalt fiber, thereby improving the interface bonding strength between the two, thereby improving the high-temperature resistance of the basalt fiber.

[0020] Preferably, in step S2, the mass ratio of the organic basalt fiber, deionized water, boric acid, and melamine is 50-60:900-1000:30-40:10-20, the temperature of the hydrothermal reaction is 150-180°C, the time is 4-5h, and the calcination process is: under an inert atmosphere, the temperature is raised to 250-300°C at a heating rate of 2-3°C / min, kept warm for 2-3h, then the temperature is raised to 500-600°C at a heating rate of 4-5°C / min, kept warm for 1-2h, and finally the temperature is raised to 850-900°C at a heating rate of 20-25°C / min, and kept warm for 20-30min.

[0021] In the present invention, boron nitride is generated in situ on organic basalt fibers via a hydrothermal method. Through specific step-by-step calcination, thermal damage to the basalt fiber matrix itself is minimized while ensuring coating formation. This also reduces the problem of defects or pores at the interface caused by gases released from the decomposition of phenolic resin, which in turn weaken the bonding strength. Both the boron nitride and the carbon layer are highly refractory materials with extremely high melting points, which slow down the softening and strength loss of the material at high temperatures.

[0022] Preferably, in step S3, the volume ratio of ethanol to water in the ethanol aqueous solution is 3:1, the mass ratio of the composite fiber and γ-mercaptopropyltrimethoxysilane is 60-70:5-8, the stirring reaction temperature is 50-60°C, and the time is 3-4h.

[0023] In the present invention, the composite fiber is modified by using γ-mercaptopropyltrimethoxysilane to provide mercapto reaction sites, which is beneficial to the subsequent reaction.

[0024] Preferably, in step S4, the mass ratio of the organic composite fiber, lauryl methacrylate, and azobisisobutyronitrile is 60-70:4-5:0.3-0.5, and the temperature of the isothermal reaction is 80-90° C., and the time is 1.5-2.5 h.

[0025] In the present invention, lauryl methacrylate is introduced into the composite fiber through a mercapto-ene reaction, introducing a flexible organic long chain. This hydrophobic surface can effectively prevent moisture from penetrating along the interface between the fiber and the matrix, significantly reducing the water absorption rate of the composite material, thereby greatly improving the service life and performance stability of the air duct in a humid environment, and reducing the strength loss, deformation or pulverization caused by moisture absorption; at the same time, the boron nitride / carbon coating itself is an inorganic substance, and its physical and chemical compatibility with the magnesium sulfate matrix is better than that of bare basalt fiber, which helps to form a stronger physical meshing and improve the mechanical properties of the material.

[0026] The present invention also protects a method for preparing the flame-retardant and high-temperature resistant material for fireproof air ducts as described above, comprising the following steps:

[0027] The raw materials are weighed according to the formula, and magnesium oxide, magnesium sulfate, expanded perlite, mica powder, quartz powder, silica fume and waterproof modifier are added to a blender and mixed for 5-10 minutes to obtain a premix. The retarder is added to water and stirred evenly to obtain a mixed liquid. The mixed liquid is then added to the premix, mixed in a forced blender for 5-8 minutes, and finally modified mineral fiber is added and stirred for 3-5 minutes to obtain a slurry. The slurry is added to a mold, pressure-formed and then cured. After the curing is completed, the flame-retardant and high-temperature resistant material is obtained.

[0028] Preferably, the pressure of the pressure molding is 2-3 MPa, and the time is 3-7 min; the curing method is: curing for 24 hours at a curing temperature of 20-25°C and a humidity of 60-70% HR, and curing for 7 days at a temperature of 30°C and a humidity of 60% HR after demolding.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] (1) The flame retardant and high temperature resistant material for fireproof air duct provided by the present invention is prepared by taking a magnesium sulfate cement system with good fire resistance as a base material, and compounding with expanded perlite, mica powder, quartz powder, silica fume and other functional fillers, and especially introducing basalt fiber that has undergone special multi-step surface modification as a reinforcement, and adding a retarder and a waterproof modifier. The resulting material not only has excellent flame retardant properties and significantly improved high temperature stability, which can effectively meet the structural integrity requirements of fireproof air ducts under fire conditions, but also takes into account good mechanical properties, low density and improved water resistance and durability, thus overcoming the shortcomings of existing fireproof air duct materials in comprehensive performance.

[0031] (2) The flame-retardant and high-temperature resistant material for fireproof air ducts provided by the present invention utilizes magnesium oxide and magnesium sulfate to form a magnesium sulfate cement matrix with natural non-flammability, and is compounded with expanded perlite to reduce the material density and improve thermal resistance. Silica fume with high reactivity is introduced to fill the pores between particles and participate in the secondary hydration reaction to generate a denser gel phase. At the same time, high-temperature resistant inert fillers such as mica powder and quartz powder are used in combination. The various components work synergistically to prepare a composite material matrix with a dense structure, good thermal stability and excellent basic fireproof performance. By adding stearate waterproof modifiers, the inherent defect of the magnesium sulfate cement system, which is poor water resistance, is effectively improved, thereby improving the long-term durability of the material.

[0032] (3) The flame-retardant and high-temperature resistant material for fireproof air ducts provided by the present invention is modified mineral fiber, which is first activated by nitric acid and pre-coated with phenolic resin to lay the foundation for subsequent treatment and introduce a carbon source; then, a dense, high-temperature stable ceramic-like coating is generated in situ on the fiber surface by hydrothermal reaction and step-by-step calcination. By selecting phenolic resin and specific step-by-step calcination, the problem of defects or pores at the interface due to the gas released by the decomposition of phenolic resin, which weakens the bonding force, is reduced. The coating significantly improves the high-temperature resistance and strength retention of the basalt fiber itself; Then, through the bridging effect of γ-mercaptopropyltrimethoxysilane and the grafting of lauryl methacrylate, a flexible interface is formed to improve the stress transfer between the fiber and the magnesium sulfate cement matrix, improve the material toughness and possibly enhance the interface durability; through multi-step modification, the mineral fiber is given excellent high-temperature stability and interface bonding with the matrix material, so that it can more effectively play the role of bearing and inhibiting crack propagation in the fire-proof air duct material, thereby significantly improving the overall mechanical properties (especially the mechanical properties at high temperature), thermal shock resistance and comprehensive performance of resisting fire damage of the final fire-proof air duct material. DETAILED DESCRIPTION

[0033] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0034] Unless otherwise specified, the chemical reagents and materials in the present invention are purchased from commercial sources or synthesized from commercially purchased raw materials.

[0035] In the present invention, the particle size of the magnesium oxide is 300 mesh, the particle size of the expanded perlite is 325 mesh; the length of the basalt fiber is 500-700 μm and the diameter is 10-15 μm; the phenolic resin is purchased from Green Union (Jining) Chemical Technology Co., Ltd. with the brand TY-2124; the particle size of the quartz powder is 400 mesh; and the particle size of the silica fume is 325 mesh.

[0036] Example 1

[0037] A flame retardant and high temperature resistant material for fireproof air ducts, comprising the following raw materials in parts by weight:

[0038] 65 parts of magnesium oxide, 40 parts of magnesium sulfate, 55 parts of water, 20 parts of expanded perlite, 12 parts of mica powder, 13 parts of modified mineral fiber, 10 parts of quartz powder, 4 parts of silica fume, 0.7 parts of sodium tetraborate, and 1.3 parts of calcium stearate.

[0039] The method for preparing the modified mineral fiber comprises the following steps:

[0040] S1. Add basalt fiber to a 20% by mass nitric acid solution at 35°C for 1.5 hours, filter, wash, and dry to obtain pretreated basalt fiber; add 55g of pretreated basalt fiber to 350g of ethanol, then add 25g of phenolic resin, and stir at a constant temperature of 65°C for 1.5 hours. After stirring, filter and dry to obtain organic basalt fiber;

[0041] S2, adding 55g of the organic basalt fiber in step S1 to 950g of deionized water, followed by adding 35g of boric acid and 15g of melamine, and hydrothermally reacting at 170°C for 4.5h. After the reaction is completed, filtering, washing, and drying, under an inert atmosphere, the temperature is increased to 280°C at a heating rate of 2.5°C / min, and kept warm for 2.5h. Subsequently, the temperature is increased to 550°C at a heating rate of 4.5°C / min, and kept warm for 1.5h. Finally, the temperature is increased to 880°C at a heating rate of 25°C / min, and kept warm for 25min to obtain a composite fiber;

[0042] S3, adding 65g of the composite fiber obtained in step S2 to an ethanol-water solution (the volume ratio of ethanol to water is 3:1), then adding 7g of γ-mercaptopropyltrimethoxysilane, stirring and reacting at 55°C for 3.5h. After the reaction is completed, filtering, washing, and drying to obtain an organic composite fiber;

[0043] S4. Add 65 g of the organic composite fiber in step S3 into 800 mL of toluene, and then add 4.5 g of lauryl methacrylate and 0.4 g of azobisisobutyronitrile. React at 85° C. for 2 h. After the reaction is completed, filter, wash, and dry to obtain modified mineral fiber.

[0044] A method for preparing a flame-retardant and high-temperature resistant material for a fireproof air duct comprises the following steps:

[0045] The raw materials were weighed according to the formula, and magnesium oxide, magnesium sulfate, expanded perlite, mica powder, quartz powder, silica fume and calcium stearate were added to a blender and mixed for 8 minutes to obtain a premix. Sodium tetraborate was added to water and stirred evenly to obtain a mixed solution. The mixed solution was then added to the premix, mixed in a forced blender for 7 minutes, and finally modified mineral fiber was added and stirred for 4 minutes to obtain a slurry. The slurry was added to a mold, pressed at a pressure of 2.5 MPa for 5 minutes, and then cured. The curing method was as follows: curing at a curing temperature of 25°C and a humidity of 65% HR for 24 hours, and curing at a temperature of 30°C and a humidity of 60% HR for 7 days after demolding.

[0046] Example 2

[0047] A flame retardant and high temperature resistant material for fireproof air ducts, comprising the following raw materials in parts by weight:

[0048] 60 parts of magnesium oxide, 35 parts of magnesium sulfate, 45 parts of water, 15 parts of expanded perlite, 10 parts of mica powder, 10 parts of modified mineral fiber, 8 parts of quartz powder, 3 parts of silica fume, 0.5 parts of sodium citrate, and 1 part of zinc stearate.

[0049] The method for preparing the modified mineral fiber comprises the following steps:

[0050] S1. Add basalt fiber to a 15% by mass nitric acid solution, immerse at 30°C for 2 hours, filter, wash, and dry to obtain pretreated basalt fiber; add 50g of pretreated basalt fiber to 300g of ethanol, then add 20g of phenolic resin, stir at a constant temperature of 60°C for 2 hours, filter, and dry to obtain organic basalt fiber;

[0051] S2. Add 50 g of the organic basalt fiber obtained in step S1 to 900 g of deionized water, then add 30 g of boric acid and 10 g of melamine, and hydrothermally react at 150° C. for 5 h. After the reaction is completed, filter, wash, and dry. Under an inert atmosphere, increase the temperature to 250° C. at a heating rate of 2° C. / min and keep warm for 3 h. Then, increase the temperature to 500° C. at a heating rate of 4° C. / min and keep warm for 2 h. Finally, increase the temperature to 850° C. at a heating rate of 20° C. / min and keep warm for 30 min to obtain a composite fiber.

[0052] S3, adding 60g of the composite fiber obtained in step S2 to an ethanol-water solution (the volume ratio of ethanol to water is 3:1), then adding 5g of γ-mercaptopropyltrimethoxysilane, stirring and reacting at 50°C for 4h. After the reaction is completed, filtering, washing, and drying to obtain an organic composite fiber;

[0053] S4. Add 60 g of the organic composite fiber in step S3 into 800 mL of toluene, then add 4 g of lauryl methacrylate and 0.3 g of azobisisobutyronitrile, and react at a constant temperature of 80° C. for 2.5 h. After the reaction is completed, filter, wash, and dry to obtain modified mineral fiber.

[0054] A method for preparing a flame-retardant and high-temperature resistant material for a fireproof air duct comprises the following steps:

[0055] The raw materials were weighed according to the formula, and magnesium oxide, magnesium sulfate, expanded perlite, mica powder, quartz powder, silica fume, calcium stearate and zinc stearate were added to a blender and mixed for 5 minutes to obtain a premix. Sodium tetraborate and sodium citrate were added to water and stirred evenly to obtain a mixed solution. The mixed solution was then added to the premix, mixed in a forced blender for 5 minutes, and finally modified mineral fiber was added and stirred for 3 minutes to obtain a slurry. The slurry was added to a mold, pressed at a pressure of 2 MPa for 7 minutes, and then cured. The curing method was as follows: curing at a curing temperature of 20°C and a humidity of 60% HR for 24 hours, and curing at a temperature of 30°C and a humidity of 60% HR for 7 days after demolding.

[0056] Example 3

[0057] A flame retardant and high temperature resistant material for fireproof air ducts, comprising the following raw materials in parts by weight:

[0058] 70 parts of magnesium oxide, 45 parts of magnesium sulfate, 60 parts of water, 25 parts of expanded perlite, 15 parts of mica powder, 15 parts of modified mineral fiber, 12 parts of quartz powder, 5 parts of silica fume, 0.8 parts of sodium tetraborate, and 1.5 parts of zinc stearate.

[0059] The method for preparing the modified mineral fiber comprises the following steps:

[0060] S1. Add basalt fiber to a 20% by mass nitric acid solution, immerse at 40°C for 1 hour, filter, wash, and dry to obtain pretreated basalt fiber; add 60g of pretreated basalt fiber to 400g of ethanol, then add 30g of phenolic resin, stir at a constant temperature at 70°C for 1 hour, filter, and dry to obtain organic basalt fiber;

[0061] S2, adding 60g of the organic basalt fiber in step S1 to 1000g of deionized water, followed by adding 40g of boric acid and 20g of melamine, and hydrothermally reacting at 180°C for 4h. After the reaction is completed, filtering, washing, and drying, under an inert atmosphere, the temperature is increased to 300°C at a heating rate of 3°C / min, and kept warm for 2h, then the temperature is increased to 600°C at a heating rate of 5°C / min, and kept warm for 1h, and finally the temperature is increased to 900°C at a heating rate of 25°C / min, and kept warm for 20min to obtain a composite fiber;

[0062] S3, adding 70g of the composite fiber obtained in step S2 to an ethanol-water solution (the volume ratio of ethanol to water is 3:1), then adding 8g of γ-mercaptopropyltrimethoxysilane, stirring and reacting at 60°C for 3h. After the reaction is completed, filtering, washing, and drying to obtain an organic composite fiber;

[0063] S4. Add 70 g of the organic composite fiber in step S3 into 800 mL of toluene, then add 5 g of lauryl methacrylate and 0.5 g of azobisisobutyronitrile, and react at a constant temperature of 90° C. for 1.5 h. After the reaction is completed, filter, wash, and dry to obtain modified mineral fiber.

[0064] A method for preparing a flame-retardant and high-temperature resistant material for a fireproof air duct comprises the following steps:

[0065] The raw materials were weighed according to the formula, and magnesium oxide, magnesium sulfate, expanded perlite, mica powder, quartz powder, silica fume, calcium stearate and zinc stearate were added to a blender and mixed for 10 minutes to obtain a premix. Sodium tetraborate and sodium citrate were added to water and stirred evenly to obtain a mixed solution. The mixed solution was then added to the premix, mixed in a forced blender for 8 minutes, and finally modified mineral fiber was added and stirred for 5 minutes to obtain a slurry. The slurry was added to a mold, pressed at a pressure of 3 MPa for 3 minutes, and then cured. The curing method was as follows: curing at a curing temperature of 25°C and a humidity of 70% HR for 24 hours, and curing at a temperature of 30°C and a humidity of 60% HR for 7 days after demolding.

[0066] Comparative Example 1

[0067] A flame retardant and high temperature resistant material for fireproof air ducts, comprising the following raw materials in parts by weight:

[0068] 65 parts of magnesium oxide, 40 parts of magnesium sulfate, 55 parts of water, 20 parts of expanded perlite, 12 parts of mica powder, 13 parts of modified mineral fiber, 10 parts of quartz powder, 4 parts of silica fume, 0.7 parts of sodium tetraborate, and 1.3 parts of calcium stearate.

[0069] The method for preparing the modified mineral fiber comprises the following steps:

[0070] S1. Adding basalt fiber into a 20% by mass nitric acid solution and immersing the solution at 35°C for 1.5 hours. After the treatment, filtering, washing, and drying the solution to obtain pretreated basalt fiber;

[0071] S2, adding 55g of the pretreated basalt fiber in step S1 to 950g of deionized water, followed by adding 35g of boric acid and 15g of melamine, and hydrothermally reacting at 170°C for 4.5h. After the reaction is completed, filtering, washing, and drying, under an inert atmosphere, the temperature is increased to 280°C at a heating rate of 2.5°C / min, and kept warm for 2.5h. Subsequently, the temperature is increased to 550°C at a heating rate of 4.5°C / min, and kept warm for 1.5h. Finally, the temperature is increased to 880°C at a heating rate of 25°C / min, and kept warm for 25min to obtain a composite fiber;

[0072] S3, adding 65g of the composite fiber obtained in step S2 to an ethanol-water solution (the volume ratio of ethanol to water is 3:1), then adding 7g of γ-mercaptopropyltrimethoxysilane, stirring and reacting at 55°C for 3.5h. After the reaction is completed, filtering, washing, and drying to obtain an organic composite fiber;

[0073] S4. Add 65 g of the organic composite fiber in step S3 into 800 mL of toluene, and then add 4.5 g of lauryl methacrylate and 0.4 g of azobisisobutyronitrile. React at 85° C. for 2 h. After the reaction is completed, filter, wash, and dry to obtain modified mineral fiber.

[0074] A method for preparing a flame-retardant and high-temperature resistant material for a fireproof air duct comprises the following steps:

[0075] The raw materials were weighed according to the formula, and magnesium oxide, magnesium sulfate, expanded perlite, mica powder, quartz powder, silica fume and calcium stearate were added to a blender and mixed for 8 minutes to obtain a premix. Sodium tetraborate was added to water and stirred evenly to obtain a mixed solution. The mixed solution was then added to the premix, mixed in a forced blender for 7 minutes, and finally modified mineral fiber was added and stirred for 4 minutes to obtain a slurry. The slurry was added to a mold, pressed at a pressure of 2.5 MPa for 5 minutes, and then cured. The curing method was as follows: curing at a curing temperature of 25°C and a humidity of 65% HR for 24 hours, and curing at a temperature of 30°C and a humidity of 60% HR for 7 days after demolding.

[0076] Compared with Example 1, this comparative example does not pre-treat the basalt fibers and coat them with phenolic resin.

[0077] Comparative Example 2

[0078] A flame retardant and high temperature resistant material for fireproof air ducts, comprising the following raw materials in parts by weight:

[0079] 65 parts of magnesium oxide, 40 parts of magnesium sulfate, 55 parts of water, 20 parts of expanded perlite, 12 parts of mica powder, 13 parts of modified mineral fiber, 10 parts of quartz powder, 4 parts of silica fume, 0.7 parts of sodium tetraborate, and 1.3 parts of calcium stearate.

[0080] The method for preparing the modified mineral fiber comprises the following steps:

[0081] S1. Add basalt fiber to a 20% by mass nitric acid solution at 35°C for 1.5 hours, filter, wash, and dry to obtain pretreated basalt fiber; add 55g of pretreated basalt fiber to 350g of ethanol, then add 25g of phenolic resin, and stir at a constant temperature of 65°C for 1.5 hours. After stirring, filter and dry to obtain organic basalt fiber;

[0082] S2. Add 55 g of the organic basalt fiber prepared in step S1 to 950 g of deionized water, followed by adding 35 g of boric acid and 15 g of melamine, and subject the mixture to a hydrothermal reaction at 170° C. for 4.5 h. After the reaction is complete, filter, wash, and dry the mixture. Under an inert atmosphere, raise the temperature to 880° C. at a heating rate of 25° C. / min and hold the temperature for 25 min to obtain a composite fiber.

[0083] S3, adding 65g of the composite fiber obtained in step S2 to an ethanol-water solution (the volume ratio of ethanol to water is 3:1), then adding 7g of γ-mercaptopropyltrimethoxysilane, stirring and reacting at 55°C for 3.5h. After the reaction is completed, filtering, washing, and drying to obtain an organic composite fiber;

[0084] S4. Add 65 g of the organic composite fiber in step S3 into 800 mL of toluene, and then add 4.5 g of lauryl methacrylate and 0.4 g of azobisisobutyronitrile. React at 85° C. for 2 h. After the reaction is completed, filter, wash, and dry to obtain modified mineral fiber.

[0085] A method for preparing a flame-retardant and high-temperature resistant material for a fireproof air duct comprises the following steps:

[0086] The raw materials were weighed according to the formula, and magnesium oxide, magnesium sulfate, expanded perlite, mica powder, quartz powder, silica fume and calcium stearate were added to a blender and mixed for 8 minutes to obtain a premix. Sodium tetraborate was added to water and stirred evenly to obtain a mixed solution. The mixed solution was then added to the premix, mixed in a forced blender for 7 minutes, and finally modified mineral fiber was added and stirred for 4 minutes to obtain a slurry. The slurry was added to a mold, pressed at a pressure of 2.5 MPa for 5 minutes, and then cured. The curing method was as follows: curing at a curing temperature of 25°C and a humidity of 65% HR for 24 hours, and curing at a temperature of 30°C and a humidity of 60% HR for 7 days after demolding.

[0087] Compared with Example 1, the composite fiber in this comparative example is prepared by calcining in one step.

[0088] Comparative Example 3

[0089] A flame retardant and high temperature resistant material for fireproof air ducts, comprising the following raw materials in parts by weight:

[0090] 65 parts of magnesium oxide, 40 parts of magnesium sulfate, 55 parts of water, 20 parts of expanded perlite, 12 parts of mica powder, 13 parts of modified mineral fiber, 10 parts of quartz powder, 4 parts of silica fume, 0.7 parts of sodium tetraborate, and 1.3 parts of calcium stearate.

[0091] The method for preparing the modified mineral fiber comprises the following steps:

[0092] S1. Add basalt fiber to a 20% by mass nitric acid solution at 35°C for 1.5 hours, filter, wash, and dry to obtain pretreated basalt fiber; add 55g of pretreated basalt fiber to 350g of ethanol, then add 25g of phenolic resin, and stir at a constant temperature of 65°C for 1.5 hours. After stirring, filter and dry to obtain organic basalt fiber;

[0093] S2. Add 55 g of organic basalt fiber in step S1 to 950 g of deionized water, then add 35 g of boric acid and 15 g of melamine, and hydrothermally react at 170°C for 4.5 h. After the reaction is completed, filter, wash, and dry. Under an inert atmosphere, increase the temperature to 280°C at a heating rate of 2.5°C / min and keep warm for 2.5 h. Then, increase the temperature to 550°C at a heating rate of 4.5°C / min and keep warm for 1.5 h. Finally, increase the temperature to 880°C at a heating rate of 25°C / min and keep warm for 25 min to obtain modified mineral fiber.

[0094] A method for preparing a flame-retardant and high-temperature resistant material for a fireproof air duct comprises the following steps:

[0095] The raw materials were weighed according to the formula, and magnesium oxide, magnesium sulfate, expanded perlite, mica powder, quartz powder, silica fume and calcium stearate were added to a blender and mixed for 8 minutes to obtain a premix. Sodium tetraborate was added to water and stirred evenly to obtain a mixed solution. The mixed solution was then added to the premix, mixed in a forced blender for 7 minutes, and finally modified mineral fiber was added and stirred for 4 minutes to obtain a slurry. The slurry was added to a mold, pressed at a pressure of 2.5 MPa for 5 minutes, and then cured. The curing method was as follows: curing at a curing temperature of 25°C and a humidity of 65% HR for 24 hours, and curing at a temperature of 30°C and a humidity of 60% HR for 7 days after demolding.

[0096] Compared with Example 1, this comparative example does not introduce lauryl methacrylate onto the modified mineral fiber.

[0097] The flame retardant and high temperature resistant materials for fireproof air ducts prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to performance tests, wherein the room temperature flexural strength was tested according to GB / T 3001-2017 "Test method for room temperature flexural strength of refractory materials"; the high temperature flexural strength was tested according to GB / T 3002-2017 "Test method for high temperature flexural strength of refractory materials"; the impact strength was tested according to GB / T 1043.1-2008, using unnotched specimens; the fire resistance was tested according to GB / T 9978.1-2008, and the test results were as follows: 8624-2012 "Classification of Fire Performance of Building Materials and Products" was used for evaluation. Water absorption: The sample was dried to a constant weight at room temperature and the dry weight was recorded. The sample was then completely immersed in water for 24 hours, removed and air-dried, and the wet weight was measured. Water absorption was calculated using the following formula: W = (W1 - W2) / W2 × 100%; where W1 is the wet weight and W2 is the dry weight. The test results are shown in Table 1.

[0098] Table 1

[0099]

[0100] As can be seen from Table 1 above, the flame retardant and high temperature resistant material for fireproof air ducts prepared by the present invention has excellent high temperature resistance and fireproof performance, as well as good mechanical properties and waterproof properties, and has good application prospects.

[0101] The above content is a further detailed description of the present invention in combination with specific implementation examples. It cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, they can make several simple deductions or substitutions without departing from the concept of the present invention, which should be regarded as falling within the scope of protection of the present invention.

[0102] It will be easily understood by those skilled in the art that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A flame retardant and high temperature resistant material for fireproof air ducts, characterized in that: Calculated by weight, it includes the following raw materials: 60-70 parts of magnesium oxide, 35-45 parts of magnesium sulfate, 45-60 parts of water, 15-25 parts of expanded perlite, 10-15 parts of mica powder, 10-15 parts of modified mineral fiber, 8-12 parts of quartz powder, 3-5 parts of silica fume, 0.5-0.8 parts of retarder, and 1-1.5 parts of waterproof modifier; The preparation method of the modified mineral fiber comprises the following steps: S1. Adding basalt fiber to a nitric acid solution for impregnation treatment, adding ethanol after the treatment, and then adding phenolic resin, and stirring at a constant temperature to obtain organic basalt fiber; S2, adding organic basalt fiber to deionized water, then adding boric acid and melamine, and performing a hydrothermal reaction. After the reaction is completed, filtering, washing, drying, and calcining to obtain a composite fiber; S3, adding the composite fiber to an ethanol aqueous solution, and then adding γ-mercaptopropyltrimethoxysilane, stirring and reacting to obtain an organic composite fiber; S4, adding the organic composite fiber to toluene, and then adding lauryl methacrylate and azobisisobutyronitrile, and reacting at a constant temperature to obtain a modified mineral fiber; The calcination process in step S2 is as follows: under an inert atmosphere, the temperature is raised to 250-300°C at a heating rate of 2-3°C / min, kept warm for 2-3 hours, then the temperature is raised to 500-600°C at a heating rate of 4-5°C / min, kept warm for 1-2 hours, and finally the temperature is raised to 850-900°C at a heating rate of 20-25°C / min, kept warm for 20-30 minutes.

2. The flame retardant and high temperature resistant material for fireproof air duct according to claim 1, characterized in that: The retarder is one or both of sodium tetraborate and sodium citrate, and the waterproof modifier is one or both of calcium stearate and zinc stearate.

3. The flame retardant and high temperature resistant material for fireproof air duct according to claim 1, characterized in that: In step S1, the mass concentration of the nitric acid solution is 15-20%, the temperature of the immersion treatment is 30-40°C, and the time is 1-2 hours; the mass ratio of the basalt fiber, ethanol, and phenolic resin is 50-60:300-400:20-30, and the temperature of the constant temperature stirring is 60-70°C, and the time is 1-2 hours.

4. The flame retardant and high temperature resistant material for fireproof air duct according to claim 1, characterized in that: In step S2, the mass ratio of the organic basalt fiber, deionized water, boric acid, and melamine is 50-60:900-1000:30-40:10-20, and the temperature of the hydrothermal reaction is 150-180° C., and the time is 4-5 hours.

5. The flame retardant and high temperature resistant material for fireproof air duct according to claim 1, characterized in that: In step S3, the volume ratio of ethanol to water in the ethanol aqueous solution is 3:1, the mass ratio of the composite fiber to γ-mercaptopropyltrimethoxysilane is 60-70:5-8, the stirring reaction temperature is 50-60° C., and the time is 3-4 hours.

6. The flame retardant and high temperature resistant material for fireproof air duct according to claim 1, characterized in that: In step S4, the mass ratio of the organic composite fiber, lauryl methacrylate, and azobisisobutyronitrile is 60-70:4-5:0.3-0.5, and the temperature of the isothermal reaction is 80-90° C., and the time is 1.5-2.5 hours.

7. A method for preparing the flame-retardant and high-temperature resistant material for fireproof air ducts according to any one of claims 1 to 6, characterized in that: The following steps are involved: Weigh the raw materials according to the formula, add magnesium oxide, magnesium sulfate, expanded perlite, mica powder, quartz powder, silica fume and waterproof modifier into a blender, mix for 5-10 minutes to obtain a premix, add the retarder into the water, stir evenly to obtain a mixed liquid; then add the mixed liquid to the premix, mix in a forced blender for 5-8 minutes, finally add the modified mineral fiber, continue stirring for 3-5 minutes to obtain a slurry; add the slurry into a mold, pressure-form it, and then cure it. After the curing is completed, the slurry is obtained.

8. The preparation method according to claim 7, characterized in that The pressure of the pressure molding is 2-3 MPa, and the time is 3-7 minutes; the curing method is: curing for 24 hours at a curing temperature of 20-25°C and a humidity of 60-70% RH, and curing for 7 days at a temperature of 30°C and a humidity of 60% RH after demolding.

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